Interactive Crystallization of a Strongly Segregated Double Crystalline Block Copolymer with Close Crystallizable Temperatures

Hierarchical ordering and multilayer structure of poly(ε-caprolactone) end-functionalized by a liquid crystalline unit: role of polymer crystallization

This study elucidates the role of polymer crystallization in the structural organization of LC end-functionalized polymers and offers a potential method to tune the hierarchical structures of end-functionalized polymers.

Nucleobase-monofunctionalized supramolecular poly(l-lactide): controlled synthesis, competitive crystallization, and structural organization

Controlled synthesis, competitive crystallization, and crystallization-driven structural organization of thymine-monofunctionalized supramolecular poly(l-lactide).

Block copolymer compatibilization driven frustrated crystallization in electrospun nanofibers of polystyrene/poly(ethylene oxide) blends

The confined crystallization behaviour of poly(ethylene oxide) (PEO) has been studied in electrospun nanofibers of the phase-separated blends of polystyrene (PS) and PEO compatibilized with polystyrene-block-poly(ethylene oxide) (PS-b-PEO) block copolymer. The PS was present as the majority component such that the electrospun nanofibers consisted of PEO domains dispersed in the PS matrix. The phase separation in the blend occurred under the radial constraint of the nanofibers which led to the formation of small-sized fibrillar PEO domains. The use of block copolymer compatibilizer resulted in a noticeable decrease in the PEO domain size in the as-spun nanofibers. Moreover, the decrease in the domain size and domain connectivity was more substantial in the thermally annealed blend nanofibers due to the suppression of the domain coalescence mechanism resulting from the localization of the PS-b-PEO block copolymer at the interface. Consequently, the fraction of PEO domains crystallizing via homogeneous nucleation increased in the compatibilized blend nanofibers due to the presence of higher number of heterogeneity free PEO domains and disruption in their spatial connectivity. Interestingly, in the compatibilized blend nanofibers consisting of low molecular weight PEO, additional crystallization event attributed to surface nucleation was observed. The surface nucleation, plausibly, resulted from the formation of wet-brush structures where the PEO homopolymers homogeneously wet the PEO blocks present at the interface. In such a scenario, the PEO crystallization occurred via surface nucleation at the domain interface. The surface nucleated crystallization was absent in the compatibilized blend nanofibers composed of high molecular weight PEO presumably due to the formation of morphology with dry-brush structures.

Confined crystallization behaviour of poly(ethylene oxide) (PEO) was studied in electrospun nanofibers of the phase-separated blends of polystyrene (PS) and PEO compatibilized with polystyrene-block-poly(ethylene oxide) (PS-b-PEO) block copolymer.

Effect of block asymmetry on the crystallization of double crystalline diblock copolymers

Monte Carlo simulation on the crystallization of double crystalline diblock copolymer unravels an intrinsic relationship between block asymmetry and crystallization behaviour. We model crystalline A-B diblock copolymer, wherein the melting temperature of A-block is higher than that of the B-block. We explore the composition dependent crystallization behaviour by varying the relative block length with weak and strong segregation strength between the blocks. In weak segregation limit, we observe that with increasing the composition of B-block, its crystallization temperature increases accompanying with higher crystallinity. In contrast, A-block crystallizes at a relatively low temperature along with the formation of thicker and larger crystallites with the increase in B-block composition. We attribute this non-intuitive crystallization trend to the dilution effect imposed by B-block. When the composition of the B-block is high enough, it acts like a "solvent" during the crystallization of A-block. A-block segments are more mobile and hence less facile to crystallize, resulting depression in crystallization temperature with the formation of thicker crystals. At strong segregation limit, crystallization and morphological development are governed by the confinement effect, rather than block asymmetry. Isothermal crystallization reveals that the crystallization follows a homogeneous nucleation mechanism with the formation of two-dimensional crystals. Two-step, compared to one-step isothermal crystallization leads to the formation of thicker crystals of A-block due to the dilution effect of the B-block.